Organic Compounds Containing Nitrogen: JEE Main 2026 Chemistry question

A hydrocarbon 'P' ($\mathrm{C_4H_8}$) on reaction with HCl gives an optically active compound 'Q' ($\mathrm{C_4H_9Cl}$) which on reaction with one mole of ammonia gives compound 'R' ($\mathrm{C_4H_{11}N}$). 'R' on diazotization followed by hydrolysis gives 'S'. Identify P, Q, R and S.